Bone matrix assignment behaviour change in Blender 2.80
There is bone_matrix in left-handed system. It makes no sense to consider the differences between versions when the wrong parameters are inputted into Blender.

bone_matrix in left-handed system:
 &lt;Matrix 4x4 ( 0.0000,  0.0000, 1.0000,  0.0000)
            ( 0.0000, -1.0000, 0.0000, -6.0000)
            (-1.0000,  0.0000, 0.0000,  6.0000)
            ( 0.0000,  0.0000, 0.0000,  1.0000)&gt;

bone_matrix in right-handed system:
 &lt;Matrix 4x4 ( 0.0000,  0.0000, 1.0000,  0.0000)
            ( 0.0000, -1.0000, 0.0000, -6.0000)
            ( 1.0000,  0.0000, 0.0000,  6.0000)
            ( 0.0000,  0.0000, 0.0000,  1.0000)&gt;